From 23cd68b7eb756fd5cc7e5ad43b8b31c32f6664f8 Mon Sep 17 00:00:00 2001
From: Ryan Hinchey <rlhinchey@gmail.com>
Date: Thu, 11 Mar 2021 11:13:53 -0500
Subject: [PATCH] fix: adding web worker and ssr support

---
 .../src/platform/browser/environment.ts         |  4 +++-
 .../src/fetch.ts                                | 17 ++++++++++++++---
 packages/opentelemetry-web/src/utils.ts         | 14 +++++++++++---
 3 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/packages/opentelemetry-core/src/platform/browser/environment.ts b/packages/opentelemetry-core/src/platform/browser/environment.ts
index ea9514e4acb..30a6814d3d0 100644
--- a/packages/opentelemetry-core/src/platform/browser/environment.ts
+++ b/packages/opentelemetry-core/src/platform/browser/environment.ts
@@ -25,7 +25,9 @@ import {
  * Gets the environment variables
  */
 export function getEnv(): Required<ENVIRONMENT> {
-  const _window = window as typeof window & RAW_ENVIRONMENT;
+  const _window = (typeof window === 'undefined'
+    ? self
+    : window) as typeof window & RAW_ENVIRONMENT;
   const globalEnv = parseEnvironment(_window);
   return Object.assign({}, DEFAULT_ENVIRONMENT, globalEnv);
 }
diff --git a/packages/opentelemetry-instrumentation-fetch/src/fetch.ts b/packages/opentelemetry-instrumentation-fetch/src/fetch.ts
index 5aa369d82b9..b263c110152 100644
--- a/packages/opentelemetry-instrumentation-fetch/src/fetch.ts
+++ b/packages/opentelemetry-instrumentation-fetch/src/fetch.ts
@@ -32,7 +32,17 @@ import { VERSION } from './version';
 // hard to say how long it should really wait, seems like 300ms is
 // safe enough
 const OBSERVER_WAIT_TIME_MS = 300;
-const urlNormalizingA = document.createElement('a');
+
+// Used to normalize relative URLs
+let a: HTMLAnchorElement | undefined;
+const getUrlNormalizingAnchor = () => {
+  if (!a) {
+    a = document.createElement('a');
+  }
+
+  return a;
+};
+
 /**
  * FetchPlugin Config
  */
@@ -359,11 +369,12 @@ export class FetchInstrumentation extends InstrumentationBase<
 
     const observer: PerformanceObserver = new PerformanceObserver(list => {
       const perfObsEntries = list.getEntries() as PerformanceResourceTiming[];
-      urlNormalizingA.href = spanUrl;
+      const urlNormalizingAnchor = getUrlNormalizingAnchor();
+      urlNormalizingAnchor.href = spanUrl;
       perfObsEntries.forEach(entry => {
         if (
           entry.initiatorType === 'fetch' &&
-          entry.name === urlNormalizingA.href
+          entry.name === urlNormalizingAnchor.href
         ) {
           entries.push(entry);
         }
diff --git a/packages/opentelemetry-web/src/utils.ts b/packages/opentelemetry-web/src/utils.ts
index 3e4e45cb8c4..8c6a1a0e866 100644
--- a/packages/opentelemetry-web/src/utils.ts
+++ b/packages/opentelemetry-web/src/utils.ts
@@ -29,7 +29,14 @@ import {
 import { HttpAttribute } from '@opentelemetry/semantic-conventions';
 
 // Used to normalize relative URLs
-const urlNormalizingA = document.createElement('a');
+let a: HTMLAnchorElement | undefined;
+const getUrlNormalizingAnchor = () => {
+  if (!a) {
+    a = document.createElement('a');
+  }
+
+  return a;
+};
 
 /**
  * Helper function to be able to use enum as typed key in type and in interface when using forEach
@@ -125,8 +132,9 @@ export function getResource(
   initiatorType?: string
 ): PerformanceResourceTimingInfo {
   // de-relativize the URL before usage (does no harm to absolute URLs)
-  urlNormalizingA.href = spanUrl;
-  spanUrl = urlNormalizingA.href;
+  const urlNormalizingAnchor = getUrlNormalizingAnchor();
+  urlNormalizingAnchor.href = spanUrl;
+  spanUrl = urlNormalizingAnchor.href;
 
   const filteredResources = filterResourcesForSpan(
     spanUrl,